Platform Settings for Dell PowerEdge Servers

Operating System Tuning Parameters

kernel.randomize_va_space (ASLR)
This setting can be used to select the type of process address space randomization. Defaults differ based on whether the architecture supports ASLR, whether the kernel was built with the CONFIG_COMPAT_BRK option or not, or the kernel boot options used.
Possible settings: Disabling ASLR can make process execution more deterministic and runtimes more consistent. For more information see the randomize_va_space entry in the Linux sysctl documentation.

Transparent Hugepages (THP)
THP is an abstraction layer that automates most aspects of creating, managing, and using huge pages. It is designed to hide much of the complexity in using huge pages from system administrators and developers. Huge pages increase the memory page size from 4 kilobytes to 2 megabytes. This provides significant performance advantages on systems with highly contended resources and large memory workloads. If memory utilization is too high or memory is badly fragmented which prevents hugepages being allocated, the kernel will assign smaller 4k pages instead. Most recent Linux OS releases have THP enabled by default.
THP usage is controlled by the sysfs setting /sys/kernel/mm/transparent_hugepage/enabled. Possible values: THP creation is controlled by the sysfs setting /sys/kernel/mm/transparent_hugepage/defrag. Possible values: An application that "always" requests THP often can benefit from waiting for an allocation until those huge pages can be assembled.
For more information see the Linux transparent hugepage documentation.

sysctl is used to change kernel parameters at run-time.
-w vm.drop_caches=3 - clears filesystem caches

This command line utility allows you to switch between user definable tuning profiles. Several predefined profiles are already included. You can even create your own profile, either based on one of the existing ones by copying it or make a completely new one.i The distribution provided profiles are stored in subdirectories below /usr/lib/tuned and the user defined profiles in subdirectories below /etc/tuned. If there are profiles with the same name in both places, user defined profiles have precedence.

Profiles Used:

Firmware / BIOS / Microcode Settings

DRAM Refresh Delay
Default: Minimum

Memory Interleaving
Default: Auto

Memory interleaving is supported if a symmetric memory configuration is installed. When set to Disabled, the system supports Non-Uniform Memory Access (NUMA) (asymmetric) memory configurations. Operating Systems that are NUMA-aware understand the distribution of memory in a particular system and can intelligently allocate memory in an optimal manner. Operating Systems that are not NUMA-aware could allocate memory to a processor that is not local, resulting in a loss of performance. Die and Socket interleaving should only be enabled for Operarting Systems that are not NUMA-aware.

DIMM Self Healing on Uncorrectable Memory Error
Default: Enabled

Post Package Repair (PPR) on Uncorrectable Memory Error
Disabling this feature may improve memory performance for some workloads.

Logical Processor
Default: Enabled

Each processor core supports up to two logical processors. When set to Enabled, the BIOS reports all logical processors. When set to Disabled, the BIOS only reports one logical processor per core. Generally, higher processor count results in increased performance for most multi-threaded workloads and the recommendation is to keep this enabled. However, there are some floating point/scientific workloads, including HPC workloads, where disabling this feature may result in higher performance.

Virtualization Technology
Default: Enabled

When set to Enabled, the BIOS will enable processor Virtualization features and provide the virtualization support to the Operating System (OS) through the DMAR table. In general, only virtualized environments such as VMware(r) ESX (tm), Microsoft Hyper-V(r) , Red Hat(r) KVM, and other virtualized operating systems will take advantage of these features. Disabling this feature is not known to significantly alter the performance or power characteristics of the system, so leaving this option Enabled is advised for most cases.

L1 Stride Prefetcher
Default: Enabled

When this setting is Enabled, the processor provides additional fetch to the data access for an individual instruction for performance tuning by controlling the L1 stride prefetcher setting. Use the recommended setting and this option will allow for optmizing overall.

NUMA Nodes per Socket
Default: 1

Allows configuration of the memory NUMA domains per socket. The configuration can consist of one whole doman (NPS1), two domains (NPS2) or four domains (NPS4).
In the case of two-socket platforms, an additional NPS profile is available to have whole system memory be mapped as a single NUMA domain (NPS0).

L3 Cache as NUMA Domain
Default: Disabled

This field specifies that each CCX within the processor will be declared as a NUMA domain.

System Profile
Default: Performance Per Watt (OS)

When set to a mode other than Custom, BIOS will set each option accordingly. When set to Custom, each option setting can be changed.

CPU Power Management
Default: OS DBPM

Allows selection of CPU power management methodology.

Default: Enabled

C-States allow the processor to enter lower power states when idle.
When set to Enabled (OS Controlled) or when set to Autonomous (if Hardware control is supported), the processor can operate in all available Power States to save power, but may increase memory latency and frequency jitter.

Memory Patrol Scrub
Default: Standard

Patrol Scrubbing searches the memory for errors and repairs correctable errors to prevent the accumulation of memory errors.

PCI ASPM L1 Link Power Management
Default: Enabled

When enabled, PCIe Advanced State Power Management (ASPM) can reduce overall system power a bit while slightly reducing system performance. NOTE: Some devices may not perform properly (they may hang or cause the system to hang) when ASPM is enabled. For this reason L1 will only be enabled for validated qualified cards.

Determinism Slider
Default: Performance Determinism

Controls whether BIOS will enable determinism to control performance.

CPU Interconnect Bus Link Power Management
Default: Enabled

When Enabled, CPU interconnect bus link power management can reduce overall system power a bit while slightly reducing system performance.

Algorithm Performance Boost Disable (ApbDis)
Default: Disabled

Fan Speed Offset
Default: Off

Configuring this option allows additional cooling to the server. In case hardware is added (example, new PCIe cards), it may require additional cooling. A fan speed offset causes fan speeds to increase (by the offset % value) over baseline fan speeds calculated by the Thermal Control algorithm.